Posted: 10/3/2008 12:28:36 PM EDT
| I was thinking about getting a gas piston system for my AR but there are more than a couple out there on the open market. I was wondering if anybody has any experience with any of them, and how they like/dislike them. Thanks for all of the input. |
| No personal experiance with AR15 "piston" systems or conversions here but from an engineering point of view piston systems are of little to no benifit and some times a detriment in the ar 15 platform. Unless your running an SBR or a can then it might be worth a second look. Or maybe just for the novelty or fun of it. |
Not to step on any ones toes either. The OA series is D.I. gas operated. the tubey thingy on top contains the ( for lack of better words ) recoil spring and linking rod. |
True, and don't worry, I have tough feet  . I said "similar".. I like the idea,, of both methods, on pistol set ups. however, having never shot an AR with either set up, in rifle nor pistol configuration. You've opened up new questions. Pro's, con's to either, expenses, maint., reliability. Good Technical Video of Gas Piston Systems. |
hate those answers... why not.. if you got the cash go for it... ive got a POF and Adams arms systems.. idk which one i like more no cons all pros lol yes like said before the one in the AKs works great |
Yet another point of view is,,, the bolt is the piston and the carrier is the cylinder.  Si guess ya allready got one. |
An answer to that question establishes expectations. If the reason is "just because" that's fine, if the reason is to turn a 2moa gun into a .5moa gun just by adding a piston system then there's likely to be an issue. From a standpoint of gas in the face the Suppressed 10.4" HK416 was a lot nicer to shoot than at least one suppressed standard direct impingement AR was but not that noticeable of an improvement over another. |
|
There's a saying that one of the industry partners uses in the tech forums. "At the end of the day, that $400 piston conversion works just as good as the $9 gas tube that it replaced." While technically true, at the end of the day, you also spend less time cleaning, and at the end of TWO days, your gun is more reliable, doesn't heat up as much, and is better off then that $9 gas tube that was replaced. WHile I love my DI guns, I'd be more then happy to upgrade to a good, proven piston system. |
So where does the hot gas go? I have shot my AK so much you couldnt hold the dang hand guard. Granted the AR will be hotter than hell also but the hot gas has to go somewhere. Me I'll stick with my DI's spend a little more time cleaning. I still cant figure out how they claim more reliability though, by comparing a AK's reliability as a base. Allot of the AK's reliability also comes from loose tolarrances, where as the AR is a much tighter platform. To me the bolt carrier does not know whats moving it, be a piston, hot gas or a hammer for that matter. We all hear the claims of AK's being buried in mud and they shot well does that not fall under the loose tolarances and not the piston? Someone have a piston AR that wants to bury it in mud than try to fire it? |
I've seen it several ways, and strangly enough, in the saying, the cost of the piston system keeps going up, while the actual price of the piston systems stays the same..... 
|
I was just going to post this so I'll add to your thread as well. I received back my RRA from Rainier Arms today after having the PWS Piston Kit put in. PWS Kit I took it down to the Kenmore range (hell on earth) to sight in and make sure it went bang. 50 rounds later, it gose bang and got sighted in. Took it home to clean tear down, see how it worked. Good: The system is the simplest of all of the piston kits out now. Very few added parts, counting parts taken off your probly adding two parts to the whole gun. No extra springs to deal with ect. Very simple. It also keeps the DI system intact, the rifle still uses the rear spring in the stock to actuate the system. I noticed no accuracy difference at all. Mind you I was shooting a 16" chrome lined barrel with iron sights on a rainy day at 50 yards. Once zeroed tho I was easily keeping every thing in a 2" circle. Not bad at all. The Bad: This is not a dig at Rainier Arms at all just what I found after 50 rounds on a new installed hunk of gear. One of the lower mounting screws was loose on the new gas block. One of the two piston screws were loose (this replace the carrier key on a standard rifle) . The worst issue was the rear screw holding the gas piston (carrier key) on was to long by a thick hair and interfered with the firing pin coder pin. This little thing fought me for an hour. I had to drill out the extra material, broke 3 drill bits doing it and generally cussed at this screw a lot. It's fixed now and is in actuality a minor thing just in a pita spot to work on. Looking back in hind sight it's very easy to fix it just took me an hr to learn how.... If I have time I will "function test it". 150 rounds rapid fire just to work it out and see if I have any issues. I may not be able to this weekend, if not.... Gump when is the next shoot? I did one of my two AR's. After I work it thrue it's paces I will decide if I will do the other, the plan now is do convert the other as well. I decided to do this after owning an Robinson XCR and shooting it quite a bit then shooting and having to clean my ar's. The amount of shit a piston system keeps out of the action is staggering, even worse when using dirty ammo like Wolf. |
Where the hot gasses go depends on the piston system. I've never really liked the idea of such systems as LWRC, the Ares drop in system, etc, where they vent the gasses from the piston to the area under the handguard. Not good. Now take the HK 416 where the expended gasses from the piston get vented out the front of the gas block and out into the open air. Thusly the gas block and piston get no hotter then a DI gas block/FSB and the bolt and carrier don't get heated up much at all. This also means that the handguards don't heat up any more then a DI system in the HK416, whereas in the LWRC, Ares, etc, heat up the handguards something fierce like the AK's do. Honestly, the biggest issue with piston conversions for the AR platform is the bolt carrier tilt. As for your mud and tolerance claims, you're way off the mark. Loose dimensions don't mean loose tolerances. Don't confuse the two. And the AR platform has plenty of play in it compared to the AK. To me, it appears as if you don't have a lot of experience with the AR platform at all. The fact of the matter is that in Eugene Stoners original sales movie, he completely buried an AR10 (DI) in sand and then picked it up and shot the shit out of it. HK took the 416 and buried it in mud, sand, water, etc, then pulled it out and shot it. In their sales vid, LWRC came up out of the water and shot the gun full of water as well. There have been plenty of examples of people treating AR's, both DI and piston, like crap or getting them dirty as hell and having them still work. Go talk to RustedAce if you wish. Hell, i've done stuff like that before myself. You underestimate the AR platform, and you obviously havn't paid attention to the history of the AR or to the modern improvements and the liturature of the current crop of piston AR platforms. |
I dont unestimate the platform at all. Shoot I have a old Bushy that has been shot, shot some more and to be honest I cant remember how many rounds through it WITHOUT a cleaning. It was kind of a lazy torture test. Now to be honest I dread the cleaning its going to need. Your right on the piston setups and my attention as I dont see the need to dump the money into one. Its a solution looking for a problem. I never really looked at HK's as being a lowly civillian I can buy one anyway. Hell I'm not in combat and if I were I doubt I would worry then either, the M16/AR platform has to me more than proved its reliability. Your point on tolarances is noted, I just know and its been a while as I have sold all but one AK and it has not been shot in years, but I just remember it being allot looser. To be honest I really dont care for the AK platform. I guess my point was a AR is manufactured tighter than a AK, maybe I'm off but lets face it we hold our standards of manufacturing much higher. Thanks for the clairification on the tollarances, I knew what I meant in my head but it came out wrong. I sould have said demensions. |
:D grumpy keep it up mang good stuff! someone always comes in to every gaspiston thread and mixes it up with AK talk... keep to the point the guy wants to no about AR systems... i have to disagree with JoshAR the PWS system aint the simplest..not to mention perm mod of the host weapon.. like i said before i have a POF never had anyprobs and the Adams arms kits..the POF has 3 parts much like an SKS has plus the new bolt carrier which reduces carrier tilt..like grumpy said depending on the kit u got the POF does vent the hot gasses under the handguard/rail and traps the grim under it also, the piston gets dirty yes but nothing comes down to the carrier..... where the Adams Arms kit has 2 parts, but you use your same bolt carrier..and it tilts some .. but that in mind this system vents the gas out front from the handguards between the gasblock and it has a adjustable gascap system the piston runs cleaning and feels smoother when shot. cuz of the 1 peice system.. much like the HK416 yes diff kits have there own pros and cons but i have had 0 probs with the two i own next ... |
|
Ah yes the Adams kit, nice kit, seems well done. It dose however have the one thing I did not want (totaly a personal perferance, posibly even a wrong choise) an added spring system. That was my one criteria I did not want an added spring in the piston system, why I went with the PWS kit. I'll beat the hell out of this kit and see what it holds up to. |
The reason I used AK talk is, isnt increased reliability and cleaning the idea behind pistons on AR's? My other point is/was a question as I dont know much/anything about piston uppers as I have not seen the need was a question of where the gas goes, and to me if it dumps like a AK then as Grumpy said it heats the handguards up, which is a valid point. No I was not in any way shape or form comparing to a AK, if you read my post I dont care for them. |
the spring adds to the reliability ... |
Huh? The spring is neither here nor there in the reliability game. Josh has a piston system that is closer related to the Ak then the rest of the current conversions. It is closer to a long stroke piston then the short stroke piston like the LWRC, HK 416, etc. The long stroke doesn't need the seperate piston rod spring because the piston rod is attached to the bolt carrier and travels the full distance during the cycle whereas in the short stroke piston guns, the piston and rod can travel rearward as little as 3/8ths of an inch while pushing on the bolt carrier before the rod stops movement and the carrier and bolt continues its rearward travel. This is when the piston and rod then return to the closed position while the action continues the cycle. The only thing the extra spring does is return the piston and rod before the cycle is complete so the carrier doesn't impact it on it's way back into battery. and cause excess wear. It really has no impact on reliability. Now for the bad news for Josh. The long stroke piston systems usually have a pretty beefy rod for a reason. With the force exerted back on the system that is off the main axis of the cycle, it places an extreme amount of tilt preassure on the op-rod. Hell, it can be so bad that even some short stroke piston systems experience this issue. HK had an issue with this in the HK G36C and had a series of bent and broken op-rods that they had to replace. Point being is that the piston system Josh bought has what amounts to an anorexic op-rod for a long stroke gas piston system. When I first saw this system taken apart, I was appaled at the size of the op-rod. They also ignored the lessons learned back in the 80's with the Rino piston conversion (one of the first ever for the AR) and bolted the carrier key to the existing bolt carrier instead of replacing the entire carrier with a one piece. Sure, it probably has a set pin to take as much stress off of the bolts as possible, but Rino learned that doesn't always work unfortunatly, and the bolts will still shear off. Every other company making pistons that started out with bolt on keys has since moved to a one piece design or a dovetail attachment. Honestly, I hate to say it but the PWS is one of the last systems I would have reccomended followed by the adams arms abortion with all the little, easy to loose pieces and complcated setup. But, all things being equal, there might be a better system on the market in awhile..... |
|
Despite arguments to the design of the PWS kit, I'm still running mine with no problems. I gotta say I'm with JoshAR on this one. |
Although I must make a correction to my previous post in regards to a system I misidentified, insofar as the extra spring, no, it does NOT reduce wear, nor does it increase reliability. If you can prove that it does either without relying on company sales material, I may change my mind, but you won't find it.
Now here's where I make my correction. I mislabeled the OPS 416 system as Adams arms. I got them mixed up in my mind and mislabeled the two. It's the OPS 416 fucked up, curved piston with all the little parts that was and is deserving of my ire, not the Adams arms. Although the Adams arms system is more like the LWRC and still has its issues such as venting under the handguard and the bolt on carrier key. Insofar as the POF system, it has its share of issues. It doesn't handle tough training courses very well so i'm weary of its performance in the "real world". The folks at Tactical Response havn't given it good marks and they see a LOT of guns run through very tough, high round intense courses and the POF's historically havn't done very well. Insofar as the other systems, once again, I will reiterate my displeasure with ALL of them on the issue of bolt carrier tilt. Only two (HK and LWRC) address the issue, and even then, they do it in what I consider a half assed manner. Making "pregnant" bolt carriers is a stopgap measure and still causes what I consider excessive wear on the reciever extension/buffer tube. I still wouldn't install an Adams arms kit in one of my guns, nor any of the others with the exception of a complete HK or LWRC system, but honestly, i'm going to wait until the right version comes out that addresses all the issues that I want addressed. These issues being venting under handguard (bad), lack of ease of maintinence (having the system entirely under the handguard without any way to remove and perform maintinence by virtue of removal of the piston through the front of the gas block) and of course carrier tilt. Many of the current crop of pistons cover some, but none cover all appropriatly in my mind. HK comes the absolute closes at this time. What I need to feel comfortable would be forward on the gas block venting, removal of the piston from the front of the gas block for maintinence, and a better carrier tilt prevention idea. Of course it will have to have a single piece carrier (no bolt on carrier key) as well. Call me a perfectionist, but I want it done right before I spend the cash on something like that. |
|
I now own several Armalite AR-10's and several POF P-308's. Both are brutally reliable. Other than the P-308's being easier to clean I don't really see any difference. I do like the P-308's ambidextrous bolt release and the reversible gas piston that throttles down the gas pressure acting on the operating rod when running a suppressor. However, in a rifle-length gas system I don't see that as really being all that necessary. Love my AR-10T, and my 20" AR-10A4 though, especially with the Geisselle DM triggers installed. The actions cycle just silky-smooth. Really want to get my hands on a Noveske N6 21" heavy and an N6 18". If I have had any complaints at all it would be in the magazines. The Armalite Gen2 M14-type magazines are super-reliable, even right out of the wrapping (of course I never had any problems with the gen 1's either). The (19-round cap) DPMS mags for the P-308's took some breaking in at first. Generally the first round in a full mag would FTF straight off the bolt release...would generally do okay pulling the charging handle all the way back and releasing smartly. Fine now though. I guess the spring pressure with the brand new mag springs was a little high at first. I guess it simply amounts to personal preference more than anything else. I think I would feel extremely well-armed with any high quality AR...piston or DI, both kick ass. |
Thanks for those posts, Grumpy. As always I learn alot from you bro! My opinion is DI's the way to go. Doesn't seem to me that the piston systems offer that much extra, cost/benefit ratio and all that. I could see buyin' a high quality piston AR by itself, but wouldn't ever waste the coin on a "conversion". Just my 2 cents, which is worth exactly 0 cents! 
|
with all that...im my opinion the LMT and AA would be the *best* at this time.. im sure this is helping the guy and anyone else wanting a piston ar Q grumpy ...would you be happy with 2 chicks at 1 time? *her left one is smaller then the right..!! i cant do this!* lol |
Grumpy, I would call you a perfectionist (well maybe) but more of a realist. I should have been more clear in my original post, but to me and this has been said time and time again, a solution looking for a problem. I may be wrong here but to design and build a system within the constraints of making it all fit in a allready design is going to create trade offs. Now the question a piston person has to ask "is it worth it?" To me no. I have not really researched it enough to give a answer, I do know what the manufacturers tell us is purly a sales pitch, to sell the piston setup. That said what do you know about LMT's setup? The reason I ask is I have heard a little about, but nothing on their web site (I know sales pitch) but I do have a MRP QCB, that I have thought would be interesting to try out one on. |
SCAR FTW |
The AR-10A4 origninally cost me around $1500. One of the POF P-308's cost me $2400. The P-308 came with a railed forearm system, a (sweet!) Timney drop-in single-stage trigger, and a VLTOR E-Mod stock already installed right out of the box. By the time I added roughly the same thing to the AR-10A4 ( a LaRue 11-inch rail, Geiselle DMR trigger assembly, and a VLTOR E-mod)...the costs for both were pretty close to being equal. Except with the P-308 you also get the silicon nickel plated and skeletonized bolt carrier, industrial hard-chromed suppressor-ready gas piston system, and cool two-chamber medieval-looking muzzle brake. So with the POF P-308, you're getting a lot of bang for your buck...pardon the pun. |